The transmission of data between controls of machines at present only takes place by means of direct links, either in the form of directly wired inputs and outputs or by means of data transmission field bus systems, while commands or instructions cannot be transmitted in this way. Commands must be given by means of operator elements or a mainframe computer. The corresponding data are transmitted as such directly between the two controls.
The hitherto known procedure is complicated, because physical inputs/outputs or the field bus system must be made available. Coincidence must be brought about on both controls, so that the inputs/outputs have the same significances. As the controls do not normally communicate directly via a field bus, but instead by means of an interposed plant programmable logic control (PLC), the latter must take account of a 1:1 mapping in the inputs/outputs. If communication between the controls is to be extended, this involves a change to the control programs of the input and output configuration (additional field bus words, additional lines for physical inputs/outputs, additional programming expenditure on the PLC side).
The problem of the invention is to overcome the indicated disadvantages and in particular permit a simplification and simple extendibility of communication between two or more controls, whilst largely eliminating fault-prone intermediate layers.